Three people were injured in a bicycle crash during the Ironman 70.3 Japan triathlon on Sunday, leaving one man in critical condition, the Aichi prefectural police revealed.

A 52-year-old man was left unconscious after hitting his head in the crash involving two other competitors during the bike leg of the course traversing the Chita Peninsula, south of Nagoya, the police said Monday.

Another male competitor, 34, sustained several broken bones, while a 22-year-old man suffered a minor leg injury.

According to the police, the accident occurred around 10 a.m. in the race that started and ended at Shinmaiko Marine Park.

The 52-year-old man drifted into the opposite lane, and caused a head-on collision with the 34-year-old man, the police said. The 22-year-old man was apparently trailing behind one of the riders and was unable to avoid the crash.

The portion of the course where the accident occurred was marked by a gentle curve, with opposing lanes marked by traffic cones.

Ironman 70.3 events consist of swimming, cycling and running legs over a total distance of 70.3 miles (113 kilometers), roughly half of the grueling Ironman Triathlon distance.

The event in Aichi Prefecture is the only Ironman 70.3 race in Japan.